Mutual Electrostatic Interactions Research Articles

Computational Investigation of a Reversible Energy Storage Medium in g-B5N3 Decorated by Lithium.

Graphene-like materials in two dimensions hold great promise for energy storage and transformation applications owing to their distinctive features, such as lightweight composition, porous geometry, etc. Among these materials, a recently discovered unit known as g-B5N3 has demonstrated high performance in energy storage and transformation. In our efforts to enhance its applicability in adsorbing energy gases, we propose a novel composite structure by decorating Li atoms on the surface of pristine g-B5N3. The electronic properties of this composite have been comprehensively investigated using a first-principles method. Our findings reveal that the added Li atoms can be securely anchored on the g-B5N3 with an adsorption energy of -3.01 eV. Furthermore, the Li atom transfers its partial 2s electrons to the g-B5N3, exhibiting considerable electropositivity. These metallic sites effectively polarize the adsorbed H2 molecules, enhancing the mutual electrostatic interactions. Each primitive cell of Li-doped g-B5N3 can adsorb up to 13 H2 molecules, resulting in a storage capacity up to 6.3 wt %. This capacity significantly surpasses the goal of 4.5 wt % set by the U.S. Department of Energy. Furthermore, the typical adsorption energy of -0.209 eV per molecule of H2 aligns with the energy range suitable for reversible hydrogen storage. This study underscores the potential of Li-doped g-B5N3 for energy gas adsorption, shedding light on further advancements in this field.

Highly-stable gradient poly(anion-π) hydrogels with superior salt-tolerant property for giant osmotic energy harvesting

Harvesting ocean salinity energy has attracted large attentions based on different kinds of asymmetric ionic membranes. Gradient polyelectrolyte hydrogels demonstrated superior power generation capacity due to their abundant charged groups and rectification behaviors. However, they generally suffer from the electrostatic screening and dramatic swelling, leading to unsatisfactory energy conversion performance. Here, an anti-swelling, salt-tolerant gradient polyanion hydrogel is reported for high-efficiency osmotic energy conversion. The gradient polyanion hydrogel is prepared by ultraviolet (UV) induced copolymerization of anionic monomer and aromatic monomer. Benefiting from the mutual electrostatic interaction and π-π conjugation interaction, the gradient polyanion hydrogel presents the outstanding anti-electrostatic screening and anti-swelling performance. As a result, they can maintain excellent cation selectivity and ionic diode effect for providing an ultrahigh power density of 16.4 W/m2 when mixing artificial seawater and river water. This new salt-tolerant gradient polyelectrolyte hydrogel provides a promising way to recover energy from seawater and wastewater.

Correlation between charge transport and lattice dynamics in La- and Y-doped Ca2MnO4 perovskites

Transition metal oxides exhibit fascinating physical phenomena and hold potential for next-generation electronic devices; therefore, fundamental understanding of their conduction mechanisms is of prime technological importance. We investigate charge transport kinetics and elastic behavior of bulk polycrystalline Ca2-xRxMnO4 oxides, where R = Y or La and 0.01 ≤ x ≤ 0.20. Analysis of temperature dependent electronic transport properties considering the nearest neighbor small polaron hopping model in combination with first-principles calculations of elastic properties indicates tight correlation between charge transport and lattice elasticity. We find that the polaron hopping energies of Y-doped compounds are lower than their La-doped counterparts, and attain minimum values of 60 and 73 meV, respectively. This is associated to softening of interatomic bonds, which is more pronounced for Y-doping compared to La-doping. This is corroborated by a fundamental model for elastically isotropic materials, indicating that the elastic energy induced by small polarons corresponds with the measured polaron hopping energies. Accordingly, the lattice shear and Young moduli, sound velocities and Debye temperatures calculated for Y-doped cells are smaller than for La-doped ones. The non-monotonous dependence of hopping energies on dopant concentration is explained in terms of polaron-polaron separation and mutual electrostatic interactions across the Mn+3-O-Mn+4 conduction path. Our study shows how charge carrier dynamics are strongly coupled with elastic properties, implying that the latter can be used to predict charge carrier mobility in oxide semiconductors.

Supramolecular assemblies based on polymeric cyclodextrin nanosponges and a cationic porphyrin with antimicrobial photodynamic therapy action

Within of the increasing requirement of alternative approaches to fight emerging infections, nano-photosensitisers (nanoPS) are currently designed with the aim to optimize the antimicrobial photodynamic (aPDT) efficacy. The utilize of less expensive nanocarriers prepared by simple and eco-friendly methodologies and commercial photosensitisers are highly desiderable. In this direction, here we propose a novel nanoassembly composed of water soluble anionic polyester β-CD nanosponges (β-CD-PYRO hereafter named βNS) and the cationic 5,10,15,20-tetrakis(1-methylpyridinium-4- yl)porphine (TMPyP). Nanoassemblies were prepared in ultrapure water by mixing PS and βNS, by exploiting their mutual electrostatic interaction, and characterized by various spectroscopic techniques such as UV/Vis, Steady-State and Time Resolved Fluorescence, Dynamic Light Scattering and ζ-potential. NanoPS produce appreciable amount of single oxygen similar to free porphyrin and a prolonged stability after 6 days of incubations in physiological conditions and following photoirradiation. Antimicrobial photodynamic action against fatal hospital-acquired infections such as P. aeruginosa and S. aureus was investigated by pointing out the ability of cationic porphyrin loaded- CD nanosponges to photo-kill bacterial cells at prolonged time of incubation and following irradiation (MBC99 = 3.75 µM, light dose = 54.82 J/cm2).

Superior Effect of Si Doping on Interfacial Reaction of LiPON Solid Electrolyte for the Silicon-Rich Oxide (SiO1/2) Anode in All-Solid-State Batteries: A First-Principles Prediction

Silicon oxide is considered an alternative silicon anode for lithium-ion batteries, possessing high lithium capacity and excellent cycling performance. However, the application of silicon oxide in a solid-state lithium battery is still not reported; exploring the atomic-scale mechanism at its interface with the solid-state electrolyte is critical for further study. In this work, atomic-scale electrochemistry of Si-, B-, and C-doped LiPON solid electrolytes for the silicon-rich oxide (SiO1/2) electrode is explored by first-principles simulations. Our calculations reveal that the interfacial stability and conductivity are significantly enhanced upon doping of Si in LiPON. The SiO1/2/LiSiPON interface presents the highest adhesion energy and the lowest interface formation energy, suggesting a superior stability of the interface. An obvious shift of the DOS curve and large charge overlap area can be observed for LiSiPON with incorporation of the SiO1/2 layer, which shows a much smaller band gap compared with primitive LiSiPON. Moreover, lithium tends to diffuse along the LiSiPON/SiO1/2 interface, and the doped elements provide a channel for lithium transport due to mutual electrostatic interaction. Our work provides theoretical guidance for designing electrode/SSE interfaces for silicon oxide-based ASSBs.

Light-Activated Interface Charge-Alternating Interaction on an Extended Gate Photoelectrode: A New Sensing Strategy for EGFET-Based Photoelectrochemical Sensors.

Integration of extended gate field-effect transistors (EGFET) and photoelectrochemical (PEC) measurement to construct highly sensitive sensors is an innovative research field that was proven feasible by our previous work. However, it remains a challenge on how to adjust the interaction between the extended gate and the analyte and study its influence on EGFET-based PEC sensors. Herein, a new sensing strategy was proposed by a mutual electrostatic interaction. Three-dimensional TiO2 and g-C3N4 core-shell heterojunction on flexible carbon cloth (TCN) was designed as the extended sensing gate. Tetracycline (TC) was also used as a model analyte, and it contains electron-donating groups (-NH2 and -OH) with negative charge. The designed TCN-extended sensing gate was negatively charged in the dark by introducing carbon vacancies with oxygen doping in the g-C3N4 shell, while it was positively charged under illustration due to the aggregation of photogenerated holes on the surface. Therefore, a light-activated PEC sensing platform for the sensitive and selective determination of tetracycline (TC) was demonstrated. Such a PEC sensor exhibited wide linear ranges within 100 pM to 1 μM and 1-100 μM with a low detection limit of 0.42 pM. Furthermore, the sensing platform possessed excellent selectivity, good reproducibility, and stability. The proposed sensing strategy in this work can expand the paradigm for developing a light-regulated FET-based PEC sensor by mutual electrostatic interaction, and we believe that this work will offer a new perspective for the design of interface interaction in PEC devices.

Phase change microcapsules with graphene nanoplates embedded polyurea shell for enhanced thermal conductivity

• Graphene nanoplates (GNPs) as Pickering emulsifiers to stabilize n-docosane. • Regenerated nanochitin can combine with GNPs via the noncovalent interaction. • GNPs greatly enhances the thermal conductivity of microcapsules by 138%. • The microcapsules exhibit good thermal regulation capacity in electronic devices. Microencapsulated phase change materials with graphene nanoplates (GNPs) embedded polyurea shell and n-docosane (C 22 ) as core material were fabricated via Pickering emulsion polymerization. GNPs was used in combination with regenerated nanochitin as Pickering emulsifiers for enhanced stability due to mutual hydrophobic and electrostatic interactions. The microcapsules with 10 wt% GNPs (GNPs10/PU@C 22 ) exhibited melting enthalpy as high as 185.5 J/g and thermal conductivity as high as 0.65 W/m·K. GNPs10/PU@C 22 was also used to prepare composite films that showed great potential in thermal management of mobile phone devices.

Direct determination of band-gap renormalization in degenerately doped ultrawide band gap β- Ga2O3 semiconductor

${\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ is emerging as a promising wide band-gap semiconductor for high-power electronics and deep ultraviolet optoelectronics. It is highly desirable to dope it with controllable carrier concentrations for different device applications. This work reports a combined photoemission spectroscopy and theoretical calculation study on the electronic structure of Si doped ${\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ films with carrier concentration varying from $4.6\ifmmode\times\else\texttimes\fi{}{10}^{18}\phantom{\rule{0.28em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}3}$ to $2.6\ifmmode\times\else\texttimes\fi{}{10}^{20}\phantom{\rule{0.28em}{0ex}}\mathrm{c}{\mathrm{m}}^{\ensuremath{-}3}$. Hard x-ray photoelectron spectroscopy was used to directly measure the widening of the band gap as a result of occupation of conduction band and band-gap renormalization associated with many-body interactions. A large band-gap renormalization of 0.3 eV was directly observed in heavily doped ${\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$. Supplemented with hybrid density functional theory calculations, we demonstrated that the band-gap renormalization results from the decrease in energy of the conduction band edge driven by the mutual electrostatic interaction between added electrons. Moreover, our work reveals that Si is a superior dopant over Ge and Sn, because $\mathrm{Si}\phantom{\rule{0.28em}{0ex}}3s$ forms a resonant donor state above the conduction band minimum, leaving the host conduction band mostly unperturbed and a high mobility is maintained though the doping level is high. Insights of the present work have significant implications in doping optimization of ${\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ and realization of optoelectronic devices.

Electrostatic Coupling in MoS2/CuInP2S6 Ferroelectric vdW Heterostructures

AbstractFerroelectric van der Waals (vdW) heterostructure have recently emerged as a low‐power, versatile device paradigm because it combines the great diversity of the 2D materials and the memory nature of ferroelectrics. The non‐volatile field effect generated by the polarization bound charge is the pivotal factor for the device's performance. Unfortunately, microscopic studies on the interplay between polarization switching and electrostatic coupling at the heterojunction remain largely overlooked. Herein, the authors investigate the electrostatic coupling phenomena of vdW heterostructures consisting of semiconducting MoS2 and ferroelectric CuInP2S6. Significant charge injection accompanying the polarization reversal appears to be the governing field effect that modulates the electronic and photoluminescent properties of MoS2, as revealed by correlated ferroelectric domain, surface potential, and photoluminescence microscopies. Conversely, the photoactivity of the MoS2 also affects the polarization stability of CuInP2S6. This work provides direct microscopic insight into the mutual electrostatic interactions in vdW ferroelectric‐semiconductor heterojunctions, which has broad implications for ferroelectric field‐effect applications.

Gallic acid-coated silver nanoparticles as perspective drug nanocarriers: bioanalytical study.

The ability of silver nanoparticles (AgNPs) to be used as drug nanocarriers has helped rapidly to invent novel strategies to treat diseases, such as cancer. The nanoparticles may offer a valuable tool to novel pH-sensitive drug delivery systems in the present scenario because of their undergoing mechanisms associated with the regulated dissolution, aggregation, and generation of oxygen radicals as well. These processes could be monitored by electrochemical (bio)sensors that are less money and time-consuming compared to other analytical approaches, however, with comparable analytical performance. In this paper, synthesized and microscopically characterized gallic acid-coated AgNPs (GA-AgNPs) are investigated using spectral and electrochemical methods. To investigate the Ag+ release, a 21-day ageing experiment is performed spectrophotometrically, finding that the peak maximum of GA-AgNPs spectra diminished by 24.5%. The highest Ag+ content was electrochemically determined in the supernatant solution after centrifugation (6.97 μmol·L−1), while no significant concentration of silver ions in solution after redispersion was observed (1.26 μmol·L−1). The interaction experiment indicates a stabilization of GA-AgNPs in the presence of long-chain dsDNA as well as a mutual electrostatic interaction with DNA sugar-phosphate backbone. This interaction mechanism is confirmed by FTIR analysis, showing a shift (1049 to 1061 cm−1 and 913 to 964 cm−1) specific to DNA phosphate bands. Finally, doxorubicin-loaded GA-AgNPs are monitored for the specific drug release in the physiological and more reactive weakly acidic microenvironment. Hereby, electrochemical (bio)sensing of GA-AgNPs undergoing mechanisms shows a huge potential to be used for monitoring of drug delivery systems at cancer therapy.Graphical abstract

Oxygen vacancy-regulated TiO2 nanotube photoelectrochemical sensor for highly sensitive and selective detection of tetracycline hydrochloride

Investigation of the mechanism of oxygen vacancy-regulated photoelectrochemical sensors for highly sensitive and selective determination of biomolecules containing electron-donating groups is an innovative research field. In this study, oxygen vacancy-regulated TiO2 nanotube arrays (Ov-TNTs) with high photoelectrochemical activity were synthesized and applied to defect tetracycline hydrochloride (TC). The synergistic effect of oxygen vacancies and Ti3+ droves Ov-TNTs with a narrow energy band to generate more photogenerated carriers under irradiation. The photocurrent response of the oxygen vacancy-regulated photoelectrochemical sensor decreased with increasing TC concentration, which could be mainly attributed to adsorption of TC, which consumed part of the oxygen vacancies on the surface of Ov-TNTs. This system had excellent linearity in the range of 0.1–1000 nM with a detection limit of 0.33 nM (S/N = 3). In addition, the sensor was highly selective for TC determination due to the mutual electrostatic interaction between negatively charged TC-containing electron-donating groups (-NH2 and -OH) and positively charged Ov-TNTs. This study provided a foundation for developing an oxygen vacancy-regulated adsorptive photoelectrochemical sensor.

Reduced graphene oxide–Nickel sulfide (NiS) composited on mechanical pencil lead as a versatile and cost-effective sensor for electrochemical measurements of bisphenol A and mercury (II)

NiS is a highly promising transition metal sulfide versatile for a sensor material owing to its superior conductivity and stability, and herein we report its first incorporation into an electrochemical sensor. Because exposure to electrolyte under electrochemical impact can easily deform NiS, thereby decreasing its electro-activity and measurement reproducibility, a strategy for optimally integrating NiS into sensors is critically necessary. For this purpose, NiS was initially firmly affixed to a mechanical pencil lead (MPL) by means of hydrothermal deposition (with the result designated as MPL-NiS). MPL, a commercially available carbon-based material with consistent quality, was adopted to make the sensor cost-effective and easily prepared. Then, to prevent direct exposure of NiS to samples during electrochemical measurement and to make the sensor surface more reactive for wide variety of analytes, reduced graphene oxide (rGO) was electrodeposited on the NiS surface to construct a final structure of MPL-NiS/rGO. In summary, NiS, a p-type semiconductor with positive charge, was effectively composited and sandwiched with negatively charged rGO and MPL by means of mutual electrostatic interaction. When the developed MPL-NiS/rGO sensor was used to separately measure bisphenol A (BPA) and mercury- Hg2+, the sensitivity and sensor-to-sensor reproducibility were comparable with or superior to those of previously reported sensors.

Molecularly imprinted membrane with innovative structure and high performance for chiral separation of amino acids

ABSTRACTAn advanced surface imprinting technique, i.e., the technique of synchronously graft/crosslinking polymerizing of monomer and imprinting of template on the surface of membrane, was designed and used, and a kind of graft-type molecularly imprinted membranes of the single enantiomer of amino acids was successfully prepared. The microfiltration membrane of chloromethylated polysulfone (CMPSF) was used as substrate membrane, and then the aminated polysulfone (AMPSF) membrane was obtained by amination modification. Whereupon, a surface-initiating system of –NH2/ was formed at the interface between AMPSF membrane and an aqueous solution, in which all of the functional monomer dimethylaminoethyl methacrylate (DMAEMA), the crosslinking agent N,N′-methylenebisacrylamide (MBA), initiator (NH4)2S2O8, and L-aspartic acid (L-Asp) as template were dissolved. In the aqueous solution, DMAEMA molecules automatically combined around L-Asp molecules by right of the mutual strong interactions, electrostatic interaction and hydrogen bonding. By initiating of the radicals produced on the surface of AMPSF membrane, the graft/crosslinking polymerization of DMAEMA and MBA took place, and at the same time, L-Asp molecules were embedded into the crosslinked networks. In this way, the grafting-type L-Asp-molecularly imprinted membrane (L-Asp-MIM) was formed. The experimental results show that L-Asp-MIM has high flux and strong mechanical strength like CMPSF microfiltration membrane, and more importantly, it possesses fine chiral recognition selectivity and excellent enantioseparation ability. The selectivity coefficient of L-Asp-MIM for L-Asp reaches 7.52 relative to D-Asp. In the permeation experiment of a raceme solution of Asp, the combination of “gate effect” and “barrier effect” makes the raceme solution of Asp to be well separated, and the optical purity (ee value) of the penetrating fluid gets up to 82%.

Electrostatic differences: A possible source for the functional differences between MCF7 and brain microtubules

Recent studies suggested a link between diversity of beta tubulin isotypes in microtubule structures and the regulatory roles that they play not only on microtubules' intrinsic dynamic, but also on the translocation characteristics of some of the molecular motors along microtubules. Remarkably, unlike porcine brain microtubules, MCF7 microtubules are structured from a different beta tubulin distribution. These types of cancer microtubules show a relatively stable and slow dynamic. In addition, the translocation parameters of some molecular motors are distinctly different along MCF7 as compared to those parameters on brain microtubules. It is known that the diversity of beta tubulin isotypes differ predominantly in the specifications and the electric charge of their carboxy-terminal tails. A key question is to identify whether the negative electrostatic charge of tubulin isotypes and, consequently, microtubules, can potentially be considered as one of the sources of functional differences in MCF7 vs. brain microtubules.We tested this possibility experimentally by monitoring the electro-orientation of these two types of microtubules inside a uniform electric field. Through this evaluation, we quantified and compared the average normalized polarization coefficient of MCF7 vs. Porcine brain microtubules. The higher value obtained for the polarization of MCF7 microtubules, which is associated to the higher negative charge of these types of microtubules, is significant as it can further explain the slow intrinsic dynamic that has been recently reported for single MCF7 microtubules in vitro. Furthermore, it can be potentially considered as a factor that can directly impact the translocation parameters of some molecular motors along MCF7 microtubules, by altering the mutual electrostatic interactions between microtubules and molecular motors.

Controlled pH- and glucose-responsive drug release behavior of cationic chitosan based nano-composite hydrogels by using graphene oxide as drug nanocarrier

Abstract To realize tight control of hyperglycemia for diabetic patients, cationic chitosan (HTCC) based nano-composite hydrogels were prepared by using graphene oxide (GO) as nano-carrier for the model drug (bovine serum albumin, BSA). BSA intercalated into the layers of GO and the intercalation process was mainly driven by the mutual electrostatic interaction. By introducing GO-BSA, a more compact GO-centered network structure formed for the hydrogel. Compared with HTCC/BSA, HTCC/2.0wt%GO-BSA hydrogels exhibited a more distinct pH-/glucose-sensitivity and a much lower initial burst release, which was attributed to the compact structure and strong interactions among HTCC, GO and BSA in the hydrogel system.

Graphene membrane encapsulated Co3O4 nanotubes with superior capacity and stability as anode materials for lithium ion batteries

The electrospun Co3O4 nanotubes encapsulated by graphene membrane are successfully synthesized via a novel and efficient method. The Co3O4 nanotubes with the diameter of ~200 nm are prepared by electrospinning combined with sintering process. Graphene is wrapped on the charge-modified surface of Co3O4 nanotubes by the mutual electrostatic interactions. The as-prepared graphene/Co3O4 nanotubes are applied as anode materials for lithium-ion batteries and show the improved rate capacities (up to 430.9 mAh g−1 at the current density of 1600 mA g−1) and excellent rechargeable stability (961.4 mAh g−1 at the current density of 100 mA g−1 after 80 cycles). The existence of graphene membrane not only decreases the lithium ion transport path due to serving as the additional transport channel, but also provides the elastic buffer to avoid the agglomeration of the Co3O4 nanotubes. The nanotubes located in the graphene could effectively prevent the agglomeration of graphene membranes, and consequently keep their high active surface area. The complementary and synergistic effect of Co3O4 nanotubes and graphene makes a great contribution to the outstanding electrochemical properties. The graphene/Co3O4 nanotubes composites were applied as anode materials and shown excellent electrochemical performance.

Effective photocatalytic dechlorination of 2,4-dichlorophenol by a novel graphene encapsulated ZnO/Co3O4 core-shell hybrid under visible light.

In the present work, a graphene encapsulated ZnO/Co3O4 (GE/ZnO/Co3O4) core-shell hybrid is fabricated through a facile self-assembly approach, where the mutual electrostatic interaction force drives the ZnO/Co3O4 heteronanostructures to be fully wrapped with flexible ultrathin graphene shells. The as-prepared GE/ZnO/Co3O4 core-shell hybrid is characterized and exhibits excellent visible light photocatalytic ability toward dechlorination of 2,4-dichlorophenol (2,4-DCP) in the aqueous phase. It is worth noting that 2,4-DCP is almost completely mineralized into CO2 and H2O by the GE/ZnO/Co3O4 after 5 h of a photocatalytic reaction. This type of higher dechlorination and mineralization efficiency of 2,4-DCP is not generally observed, and is found to be higher than some previous studies. The dechlorination of 2,4-DCP has been achieved under different parametric conditions. The unique architecture of the GE/ZnO/Co3O4 core-shell hybrid also provides high stability and recyclability towards degradation of 2,4-DCP. The higher photocatalytic activity of the hybrid can be ascribed to the synergistic effect of ZnO, Co3O4 and graphene, and also by an increase in the contact surface between the metal oxide core and the graphene shell, which acts as a continuous path for rapid electron transport to offer a greater number of reactive species.

Design and preparation of matrine surface-imprinted material and studies on its molecule recognition selectivity

A matrine molecule surface-imprinted material was designed and prepared using an effective surface-imprinting technique developed by our group, and its molecular recognition performance and mechanism were investigated in depth. Monomer glycidyl methacrylate (GMA) was first graft-polymerized on the surfaces of micron-sized silica gel particles in surface-initiated graft polymerization manner, obtaining the grafted particles PGMA/SiO2 with high grafting degree. Subsequently, the ring-opening reaction of the epoxy groups of the grafted macromolecules PGMA with 5-aminosalicylic acid (5-ASA) was carried out, resulting in the functional grafted particle SA-PGMA/SiO2, on whose surfaces salicylic acid as functional group was chemically bonded. By right of the mutual strong secondary bond forces, electrostatic interaction and hydrogen bonding, SA-PGMA/SiO2 particles produced strong adsorption for matrine. Finally, with this strong adsorption, matrine molecule surface imprinting was carried out on the surfaces of SA-PGMA/SiO2 particles with ethylene glycol diglycidyl ether as cross-linking agent, resulting in the matrine molecule surface-imprinted material MIP-SAP/SiO2. The binding characteristic of MIP-SAP/SiO2 toward matrine was investigated in depth with both batch and column methods and using oxymatrine and cytisine as two contrast alkaloids. The experimental results show that MIP-SAP/SiO2 has special recognition selectivity and excellent binding affinity for matrine. Relative to oxymatrine and cytisine, the selectivity coefficients of MIP-SAP/SiO2 for matrine are 5.66 and 11.17, respectively.

Superior lithium storage performance using sequentially stacked MnO2/reduced graphene oxide composite electrodes.

Hybrid nanostructures based on graphene and metal oxides hold great potential for use in high-performance electrode materials for next-generation lithium-ion batteries. Herein, a new strategy to fabricate sequentially stacked α-MnO2 /reduced graphene oxide composites driven by surface-charge-induced mutual electrostatic interactions is proposed. The resultant composite anode exhibits an excellent reversible charge/discharge capacity as high as 1100 mA h g(-1) without any traceable capacity fading, even after 100 cycles, which leads to a high rate capability electrode performance for lithium ion batteries. Thus, the proposed synthetic procedures guarantee a synergistic effect of multidimensional nanoscale media between one (metal oxide nanowire) and two dimensions (graphene sheet) for superior energy-storage electrodes.

Spin Exchange Between Charged Paramagnetic Particles in Dilute Solutions

Kinetic equations for the spin density matrix which take into account binary collisions and a method of calculating the spin exchange effective radius have been generalized to the case of dilute solutions of charged paramagnetic particles. The effective radius of the spin exchange and rate constant of the bimolecular spin exchange between charged paramagnetic particles in solutions have been calculated numerically. Calculations have been performed under the assumption that the exchange interaction is isotropic and decays exponentially with the increase in the distance between radicals, and the solution has a given dielectric permittivity and Debye screening radius. Dependences of the spin exchange rate constant on the mutual diffusion coefficient, exchange and electrostatic interactions parameters have been found numerically. The theory has been applied to experimental results taken from the literature. The rate constant of the spin exchange between radicals of like charge found from the experiment and calculated within the developed theory are in good qualitative agreement .